Ok I'm sick of my tank light, I have the normal 15W yellow-ish light (that one came with the tank) (you know the light that normal light bulbs produce) the light that comes out of them tends to be on the yellow-ish side.

I was just wondering, if I got those fluorescent's or something lights, you know the one's with the blue undertone's, the light come's out white rather than yellow. If it will hurt the fish

What kind of tank do you have? Usually the instructions that come with the tank tell you the maximum CFL bulb size you can use in the tank. I use daylight spectrum CFL bulbs in both my tanks. It definitely will not hurt your fish as long as you get the correct wattage.

I have an Aquaeon 2.5 gallon desktop kit, on the box it tells me to put a 15W incandescent bulb, but the one that came with the tank is yellow-ish and i can barely see my fish.
I bought some new one's to have some back-up one's when the tank one goes out, their 15W clear one's.

The CFL bulbs are cheaper at target or walmart than Petsmart. Petsmart really rips you off. But you need to see if they will fit. I have to use the MINI CFL bulbs. Regular size won't fit in my tank. They are the spiral ones you see in stores. I use a 10 watt bulb (the max I can use is a 11). The biggest thing though is if the bulb will fit in the spot for your tank.